Jim Hall Says ATR 42, Q400 Have Inherent Risks In Icing Even as the National Transportation Safety Board continues its investigation into the downing of Continental Connection Flight 3407 near Buffalo, NY -- and investigators take pains to note it's too soon to draw any conclusions about what caused the fatal crash -- a former head of the NTSB says all twin-engine turboprop airliners should be grounded immediately. The Toronto Star reports Jim Hall -- who was appointed by then-President Clinton to head up NTSB in 1994, and left in 2001